1. Field of the Invention
The present invention relates to a method for displaying a character that moves in a virtual three-dimensional space in a three-dimensional video game.
2. Description of the Related Art
In the three-dimensional video game, a player character, which operates according to an instruction sent from a game player, moves in the virtual three-dimensional space. Perspective transformation is performed on the virtual three-dimensional space including the player character from a predetermined position (a view point of a virtual camera) onto a virtual screen. An image indicating the state that the player character moves is displayed on a display device.
Movement of the player character is the most important element for the progress of the game. Accordingly, in order to display the player character to be easily understandable for the player, it is necessary to move the position of the view point in accordance with movement of the player character. A conventional video game that moves the position of the view point in accordance with movement of the player character, moves the position of the view point to maintain a fixed interval between the position of the player character and that of the view point.
However, if the distance between the position of the player character and that of the view point is always kept constant, the size of the player character in an image displayed on the display device is not changed at all. For example, in the case where a field having few landmarks such as a desert is formed in the virtual three-dimensional space, an image to be displayed is changed only slightly even if the player character moves in the field area. As a result, the player cannot clearly recognize the fact that the player character moves from the image formed on the display screen. In this method, the position of the view point must be determined for each frame, increasing an amount of processing.
In contrast to this, there is a video game that performs perspective transformation after fixing the position of the view point completely. In this case, if the player character moves, the size of the character to be displayed is changed. In the case of a game such as a battle game having a narrow space where the player character is movable, no major problem is caused even if the aforementioned method is used. However, in the case of a game such as a role playing game having an extremely wide space where the player character is movable, there is a case that the position of the player character is so close to the view point that the field cannot be displayed on the display screen, or a case that the position of the player character is so far from the view point that the size of the player character to be displayed is reduced, with the result that the player character is barely seen.
Unexamined Japanese Patent Publication Nos. 11-4963 and 11-7543 disclose techniques that first and second displayed objects exist in a virtual space and a view point of a virtual camera is moved or an angle of view thereof is changed based on the positional relationship between the first and second displayed objects.
However, there are many video games that progress a game even if two displayed objects do not exist unlike the cases described in the aforementioned publications. For example, there is a video game such as a role playing game in which the player character moves on a field formed in the virtual three-dimensional space. The techniques described in the above two publications cannot be applied to such a video game.